This invention relates to a method and apparatus for controlling refrigeration apparatus. An example of the application of the invention is to a method and apparatus for controlling the operation of domestic and commercial food storage refrigeration apparatus including deep freeze apparatus. However, the invention also provides, as such, the apparatus which operates in accordance with the aforesaid method for controlling such refrigeration apparatus, and provides temperature sensing apparatus.
Further aspects of the invention relate to the use of the method and apparatus for the control of apparatus for raising the temperature of food and the like, for example microwave cooking apparatus. Further aspects of the invention relate to a method and apparatus for conducting thermal tests and calibration in relation to refrigeration and heating apparatus.
There is disclosed in WO 94/10546 (reference P51957WO) a method and apparatus applicable to temperature sensing in relation to refrigeration equipment in which provision is made for a means to enable visual inspection, of temperature sensing apparatus (for example a conventional bulb and meniscus column-type thermometer) which has been stored in a refrigerator and then removed for inspection, without the attendant inaccuracy of temperature measurement arising from immediate response of the thermometer to the raised air temperature outside the refrigerator or, if such inspection is effected without removal from the refrigerator, the effect of the ingress of external warm air into the refrigerator.
For this purpose, the apparatus of the WO 546 specification provides for the thermometer to be entirely encased within a transparent capsule containing ethylene glycol.
In this way the WO 546 apparatus seeks to offset the effect of sudden changes of air temperature on temperature sensing apparatus used in relation to refrigeration equipment.
In a similar way, the disclosure in DE 30 32 684 A1 provides for the use of a thermal barrier material to surround the temperature sensor in a refrigerator in order that the effect of opening the door of the refrigerator will be cushioned.
In the references cited against the WO 546 specification there are related disclosures concerning the use of thermal inertia and barrier systems for similar or related reasons.
We have discovered that the technical approach adopted in these prior proposals to the sensing of temperatures in refrigeration apparatus and to the control of such apparatus, is technically subject to significant shortcomings in terms of seeking to alleviate the symptoms of the mallaise (inaccurate temperature sensing) without looking to see what is the actual technical step needed for the purpose in terms of the real function of the temperature sensing system.